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Ichthyosaurs were raptorial marine reptile that could grow to enormous size of it and ruled the sea during part of the dinosaur era . For a chunk of the zillion of year whendinosaursreigned over Earth ’s landmass , ichthyosaurs claimed the title as maritime apex predator .
These monolithic " ocean monsters " appeared on Earth about 250 million year ago , just before the emergence of dinosaur ( around 230 million days ago ) , and ichthyosaur snuff it off about 90 million class ago , just before the nonavian dinosaur choke out , closely 66 million year ago . ichthyosaur radiate into a mixture of physical structure plans , but you could summarize their evolution as early , eel - like forms transitioning into the dolphinfish - same appearance typical of most subsequently ichthyosaur species , saidevolutionary life scientist Ryosuke Motani , a professor in the Department of Geology at theUniversity of California Davis .
This is a 3D science rendering of an Ichthyosaur stenopterygius, a large extinct marine reptiles from the Early Triassic to Late Cretaceous period.
Are ichthyosaurs considered dinosaurs?
Do n’t get horse around by that " -saur " suffix : Despite occupying the same Mesozoic era as the dinosaur , ichthyosaurs were no dinos . Instead , alongside other such ocean creatures like plesiosaurs andmosasaurs , they belonged to a separate radical of archosaurian — marine reptiles .
Despite accept a streamlined consistency , cinque and an elongate oral sex with a pointed nose , reptilian ichthyosaurs are n’t closely related to dolphin or fish , either . Instead , in an example ofconvergent phylogenesis , divers and unrelated linage of swimmers — mammalian like dolphins , fish like sharks and sturgeons , and ancient reptiles like the ichthyosaurs — came to resemble one another because of similar evolutionary pressures . " Subjected to the same environmental force , Pisces , aquatic reptiles and aquatic mammalian severally evolved standardized shape because a streamlined consistency is the most efficient way of affect through the dumb mass medium of water,“wrote John Blamire , a professor of biology at Brooklyn College in New York .
In " The Panda ’s Thumb " ( W. W. Norton and Co. , 1992 ) , naturalist Stephen Jay Gould nominated the ichthyosaur as " the most staggering " object lesson of convergent evolution on record . " This sea - break down reptile with terrestrial ancestors converged so strongly on fishes that it actually evolve a dorsal fin and tail in just the right position and with just the right hydrological design , " Gould indite . The ichthyosaur stay on a reptile through and through , however , Gould continued , " from its lungs and surface breathing to its flipper made of modified ramification bone , not pentad rays . "
A photo of an ichthyosaur fossil at the North Carolina Museum of Natural Sciences.
That hyperspecialization to the sea makes immobilise down ichthyosaurs ' lineage take exception , according to the University of California Museum of Paleontology ( UCMP ) . They may form an offshoot of the diapsid reptile , a large mathematical group of related organisms that also include dinosaurs , bird and Snake River . Or they may come from a distant turtle congenator .
However ichthyosaurs develop , recent studies have shown that they erupt onto the scene , evolutionarily speaking . A2016 cogitation describingan early ichthyosaur advise that the group first appear after the end - Permian mass quenching — Earth ’s greatest mass experimental extinction , which come about 251.9 million years ago — and then quickly diversify into fresh shape . The ichthyosaur described in the discipline , Sclerocormusparviceps , had an atypical anatomy , with a toothless , stubby nozzle that it may have used to suckle up food . That leftover invention point that " ichthyosauriforms evolved and branch out chop-chop , " said Olivier Rieppel , a conservator of evolutionary biology at The Field Museum in Chicago . " These ichthyosauriforms seem to have evolved very quickly , in scant flare-up of lots of change , in leaps and bounds,“Rieppel said in a statementabout the uncovering .
— Meet ' Fiona ' the pregnant ichthyosaur , Chile ’s oldest marine reptilian ma
A direct comparison of two ocean giants from different epochs side by side: The Triassic ichthyosaursvs. today’s sperm whale, with human for scale.
— The world ’s gravid ichthyosaur may have just been get wind in the Swiss Alps
— This 130 million - year - former ichthyosaur was a ' hypercarnivore ' with knife - like teeth
Ichthyosaurs also took an evolutionary fast - track to achieve their smashing size , researchers report in 2021 . A newfound species , Cymbospondylus youngorum , would have elongate more than 55 feet ( 17 meters ) long ground on extrapolation from its 6.5 - foot - long ( 2 m ) skull , scientistsreported in the journal Science . But the enormous puppet appear only about 2.5 million geezerhood after ichthyosaur ' first appearance , or within 1 % of their 150 million years on the planet . By equivalence , whales plodded along for 90 % of their 55 million year before get so gravid .
The ichthyosaur tooth is 4 inches long (10 cm), and missing part of its crown. The beast that bore it may be one of the largest sea monsters ever.
How big were ichthyosaurs?
Not all ichthyosaur got so girthy . The representativeIchthyosaurusgenus , which gives the large mathematical group its name , traverse about 10 pes ( 3 m ) long on average and search very fish - like , according to Britannica . Most ichthyosaur were much smaller than their biggest cousins , such as several species ofIchthyosaurusfound in the United Kingdomstretching just 5 to 11 feet(1.5 to 3 m ) . The general ichthyosaur length ranged from 3 to 65 feet ( 1 to 20 m ) , with an average length of 6.5 to 13 feet ( 2 to 4 m ) . Some measured under 3 feet ( 1 m ) long , while theChaohusaurus geishanensisspecies was in all likelihood smaller than 28 inches ( 70 centimeter ) long and some species could be as tiny as 1 understructure ( 0.3 m ) long .
But by the previous Triassic catamenia , several ichthyosaur species arrive at great size of it , Britannicasaid . Shonisaurus popularisand others could outperform 50 feet ( 15 m ) long , Motani write , while a 2004 specimen reach anestimated 69 feet ( 21 m)in distance . A more recent discovery suggests that some ichthyosaurs rivaledblue whalesin size . In 2018 , scientistsreportedfinding fragments of a monumental , 3.1 - foot - long ( 96 cm ) ichthyosaur jawbone , which scale up to hint at a organic structure that would have measured around 85 feet ( 26 m ) or more . That ’s 25 % turgid than the previous , 69 - foot - long record bearer . By comparison , profane whales amount in at 80 to 100 feet ( 24 to 30 m ) long .
" Biology textbook[s ] have long touted the innovative blue heavyweight as the largest animal that ever populate , but this and other fascinating fogey finds hint that there may once have been even self-aggrandising brute swim Earth ’s seas,“National Geographic wroteabout the 2018 find .
A toothunearthed in the Swiss Alps in 2022hints at an even big ichthyosaur . At 4 inches ( 10 cm ) long and 2.3 in ( 6 cm ) wide , the low chomper is twice as panoptic as the previous record - bearer for ichthyosaur teeth , which come from a beast nearly 50 animal foot ( 15 m ) long . Because investigator have only part of a tooth to go on , however , they do n’t yet hump if this find represents one of the prominent ichthyosaur or just one with a peculiarly telling grin .
For those wondering if they could bench press an ichthyosaur , Motani supply somerough estimateson weight , warning that guess the torso people of extinct animal " usually involves many premiss . " small ichthyosaur species like the 1.5 - substructure - long ( 0.45 m)Stenopterygiusweighed in at an estimated 2 pounds ( 0.9 kilograms ) , while larger model like the 13 - foot - tenacious ( 3.9 m)Ophthalmosaurus icenicusmay have carried about 2,070 Ezra Loomis Pound ( 940 kg ) of mass .
What did ichthyosaurs eat?
carnivore to their inwardness , ichthyosaurs feed on ocean beasts large and small . big species din onsquid , Pisces the Fishes and other maritime tool . Studies of belly cognitive content from the fish - shaped ichthyosaur provide evidence of that diet , Motani notice , with studies decease back as far as 1853 documenting hooklets from squid - similar creature , such as belemnites , in ichthyosaurs ' stomachs . In their preference for calamari , ichthyosaurs resembled modern whales , Motani said .
Exceptionally gravid heart in some mintage may have aided in deep - sea dive tohunt calamari — or in descry other predators , like plesiosaur . In the only modern animals with similarly mammoth peepers , the colossal and giant squids , such eye give more to spy and avoiding thirsty whales than hunting dinner , scientists explained in a study publish in 2012 in the journalCurrent Biology .
But because ichthyosaur cast widely in size and existed for so long , they likely subsisted on a variety of fair game gathered in a variety of room . braggart ichthyosaurs , like the large Triassic - periodThalattoarchon , feature dangerous teeth that were in all likelihood used for catchingprey the animals ' own size of it , while short - snouted brute like theGuanlingsaurusmay have swear onsuction feeding . Later , larger ichthyosaur ' shape , qualify by long fin and bodies that were thick from back to venter , evoke they track down by ambushing fish , concord to Britannica .
A Cretaceous ichthyosaurdescribed in 2021likely terrorize ancient prey with its horrendous teeth . CalledKyhytysuka sachicarum , the beast was hear in primal Colombia and wielded more and larger knife - similar teeth than any other ichthyosaur species . " Whereas other ichthyosaurs had small , equally sized tooth for feeding on small prey , this Modern species modified its tooth sizes and spacing to ramp up an arsenal of teeth for dispatching declamatory prey , " paleontologist Hans Larsson , an associate prof at McGill University ’s Redpath Museum in Montreal , Canada , said of the discovery .
When and where did ichthyosaurs live?
As ichthyosaurs swam Earth ’s ocean for 160 million years ( from 250 million to 90 million years ago ) , they had ample time to pass around around the ball . And as creatures of the sea , they could ramble far and panoptic . The earliest recover from the lower Triassic have pop up in sites from Canada toChinaand Japan , as well as the island of Spitsbergen in Norway , Motani wrote for UCMP . By the middle Triassic , ichthyosaurs had achieved globose statistical distribution , scientists report in 2002 in the journalPaleontological Society Papers , and since the late twentieth 100 , researchers have identified and named ichthyosaurs on all seven continent .
The creature ' " very full geographic distribution " is preserved in fossils from southern Germany , England , the western United States and Canada , according to Britannica . find in the twenty-first century have cropped up from thesouthernmost tip of Chile ’s Patagonia regionin 2003to Alaskain 2014 , with a find representing the " northernmost appearance of a well - keep Triassic ichthyosaur . "
The wight ' range of eating habits helped ichthyosaur species accommodate to a range of sea environments , as well . In the 2002 bailiwick , scientists mention that ichthyosaur alimentation realm varied from nearshore during the Triassic to pelagic ( neither skinny to the seafloor nor the shore ) during the Jurassic and Cretaceous . Deep - diving ichthyosaurs could plunge down to 2,000 feet ( 600 m ) .
Whereas ichthyosaur evolve from res publica - ground reptilian that returned to the sea , much as dolphins and whales come up from re - oceaned mammals , the ancient ocean beasts were improbable to crawl onto landed estate , according to Britannica : " If stranded ashore , they would have been as incapacitated as beached whales . "
Additional resources
See ichthyosaur fogey and models , as the iconic marine reptile conjoin other " Monsters of the Deep " in a newexhibit at the Field Museumin Chicago . Learn about apregnant ichthyosaurthat was recently excavated in Chile . And did you know that ichthyosaurs and other ancient marine apex marauder sometimesfed upon each other ?
Original article on Live Science .
